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Topic: Objective2 (O2) Headphone Amp DIY Project (Read 9938 times) previous topic - next topic
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Objective2 (O2) Headphone Amp DIY Project

Those who are interested in headphone amps, DIY projects, and/or what happens when you toss an objective hand grenade into a room full of subjectivists, might find this project interesting:
  • I've documented the design of an inexpensive portable/desktop headphone amp that was designed to well defined objective criteria.
  • I've fully measured the performance using professional instrumentation and published all the results.
  • I've released under a Creative Commons license as open source hardware.
  • I've conducted informal blind ABX testing against a much more expensive commercial product with no difference discernible.
  • I have zero commercial or financial interest in this project.

Without any participation from me, any mention of the design by several different people was initially immediately deleted by the admins of a certain large headphone forum. Eventually a thread was allowed with very restrictive rules and its been heavily censored as well. The admins and a couple other commercial interests have been actively trying to derail the thread.

It would seem those drinking the subjective Kool Aid don't appreciate someone coming along and challenging the status quo. And it's obvious certain commercial interests don't appreciate it either.

Despite the less than warm reception by some, there are already over 200 orders for the initial PCB group buy (out of the UK no less). If anyone here is interested in the project, I would welcome more feedback?

I've written well over 40,000 words documenting the project but there's a reasonably short summary here with links to all the details:

O2 DIY Headphone Amp

Objective2 (O2) Headphone Amp DIY Project

Reply #1 –
Quote
Without any participation from me, any mention of the design by several different people was initially immediately deleted by the admins of a certain large headphone forum. Eventually a thread was allowed with very restrictive rules and its been heavily censored as well. The admins and a couple other commercial interests have been actively trying to derail the thread.

It would seem those drinking the subjective Kool Aid don't appreciate someone coming along and challenging the status quo. And it's obvious certain commercial interests don't appreciate it either.
  Add a couple of vacuum tubes and the "audiophiles" will love the warm sound!

Objective2 (O2) Headphone Amp DIY Project

Reply #2 –
Quote from: DVDdoug on
Add a couple of vacuum tubes and the "audiophiles" will love the warm sound!

Yeah. It's a rather polarizing approach. Even the companies making gear that objectively measures and performs well usually try to avoid offending the snake-oil crowd. But, with no commercial interests to worry about, I figured I'd just tell like it is. Those who prefer tubes, for example, are free to just ignore the whole project. It's no loss to me.

I also put a $500 (to charity) blind challenge on the table but, despite 10,000+ hits to the article since, there's not been a single nibble.

I hope to arrange some future blind tests. I know many (especially those relatively new to the hobby) are curious about them. At an event like Can Jam it would be eye opening to have a "see how your headphone amp compares" table set up with an ABX box. The person working the table might need some big body guards though. It would be sort of like an atheist setting up a booth at Bible Camp!  In reality, unless you were sly about it, I doubt the organizers would ever let anyone set up a table like that.

Objective2 (O2) Headphone Amp DIY Project

Reply #3 –
I was curious to look at the thing itself, like the circuit diagram, board, parts lists, etc. Maybe I'm missing something, but all I could find, except for a lot of statements, was the link to Google Documents. I can't find any way to download from there and almost everything there is too tiny to see what it actually is. Is it possible to download something useful that can be studied at leisure?

Objective2 (O2) Headphone Amp DIY Project

Reply #4 –
There's a file menu under the Google Documents logo on the top left corner that lets you download the original PDF.

Objective2 (O2) Headphone Amp DIY Project

Reply #5 –
Quote from: AndyH-ha on
I was curious to look at the thing itself, like the circuit diagram, board, parts lists, etc. Maybe I'm missing something, but all I could find, except for a lot of statements, was the link to Google Documents. I can't find any way to download from there and almost everything there is too tiny to see what it actually is. Is it possible to download something useful that can be studied at leisure?

There's also a "+" button on the left in Google Docs that zooms in for the both the PDF and spreadsheet. The Google Docs interface is a bit spartan but it works reasonably well once you figure out where stuff is.

If anyone has problems with Google docs there are also large PNG images of the schematic, board drawing and BOM spreadsheet in the following sections of the O2 Details article:

Circuit Description (schematic)

Obtaining The Components (BOM/parts list)

Enclosure Options (board drawing)